Biologist Answers Biology Questions From Twitter

Biologist Thor Hanson answers the internet's burning questions about biology.

How do extinct species come back?

How will the human species evolve?

Are viruses alive?

Thor answers all these questions and much more!

- And you're okay withthe full frontal on this?We'll let the Twitter-verse comment on it.Hi, I'm Thor Hanson,author, and biologist.Today, I'm here to answeryour questions on Twitter.This is biology support.[upbeat music]@Jerre_Peeters asks, "Are viruses alive?"Let me answer that questionwith another question.What does it mean to be alive?Most biologists define lifeas an organism with cellsthat respond to theirenvironment and an organismthat can reproduce itself.Viruses don't meet that definitionbecause they do not have cells.They reproduce only by co-optingthe reproductive capabilitiesof a living cell.Yet, we see viruses havinga very direct impacton our lives and the lives ofother creatures in this world.So it just goes to show us thatthe very definition of lifeis still in some ways, open to question.@subnomnomnom asks, "Why are succulentssuch finicky, little bitches?"A succulent plant livesin a particular condition,out in the wild, where they have adaptedto really dry situationswhere they need to holda lot of water in their leaves,and those are difficultconditions to replicateinside your house, whichis part of the reasonthey can be very difficultto keep as houseplants.@HeyAdrienne asks, "Seeds are interesting.Who knew that when you eat one,you're eating little plant embryos?"It's hard to imaginehow small a seed can beuntil you meet the seeds of an orchid.These come from a smallorchid in our floracalled the SpottedCoralroot, and each seedis like a mote of dust, only afew cells organized together.There are approximately 1million Spotted Coralroot seedsin this vial, whichstands in stark contrastto the world's largestseed, the double coconut,which grows on palm treesfound only on two islandsin the Seychelles archipelago,isolated out in the middleof the Indian ocean.And a full-sized doublecoconut can weigh 40 pounds,11 orders of magnitudelarger than an orchid seed.So ask yourself, "Where else in nature,can you find somethingso different in formthat has the same function?"@rbatra01 asks, "DoesDarwin's theory of evolutionapply to plants also?"Yes.@HungLee asks, "Dumb question time:do you think Archaeopteryxwould have made a good pet?"This replica of an Archaeopteryx fossilhangs on the wall in my office,and I look at it every day,and biologists have beenlooking at this fossilfor over 150 years.Some call it the Rosetta Stone of biology,because it contains so muchinformation about evolution,and it reveals a creaturethat displays characteristicsof reptiles and of birds.This is one of the first fossilsthat gave people an inklingthat, in fact, the birdsare living dinosaurs.Look at the mouth of it up close,you would see little teeth.It is what some people at the time,it was discovered calledevidence of a missing link,if you will, evidence ofevolution in progress.We know that it lived in the trees.If you look at the feathers,they are like modern feathers,offset and aerodynamic on the wings,which indicates it was soaringor flapping at the time,so it would have been amessy pet to have aroundin the house, knockingthings over and so forth,and it might've given you a nasty bitebecause it had teeth.Overall, it's such an important creaturethat I think any biologistwould love to have one as a pet.@jonmacelive sent apicture with a question."Bones found while walking in the woods.Any idea of what it was?Bigger than my 50 lb dog."You are looking at the skeleton of a deer,and if you look closely, you will seethat something is missingfrom that skeleton.You have the top of theskull, and it so happensthat I have the jawbone froma deer skull right here.This part has teeth in the front,but if you were to go back inthe woods and look at the topof that skull, you wouldfind just a bony plate,no top teeth on a deer.They are pinch-and-tear herbivores,meaning they pinch the vegetationwith their bottom teethagainst that bony plate,and then tear it off,so you can always tell whenyou're out in your garden,whether it's been a deerattacking your favorite shrubberyor whether it's beensomething like a rabbitthat makes a clean cut becausedeer always leave a rough cuton the end of the vegetationthat they've been nibbling.@RJ_Zenith asks, "Can dogsand foxes be crossbredor are they too different?"So dogs and foxes are in different,what biologists or taxonomistswould call, genera.They have a different genus.They're not closely related.They're very, very distant cousins.They cannot interbreed andproduce viable offspring,whereas dogs and wolvesare closely related.In fact, dogs descend from wolves.They were domesticated from wild wolvesonly 40,000 years ago,which isn't that longin evolutionary time, so thosetwo can definitely hybridize,and they often do.@ndea_alese16 asks, "Likehow the hell did a fishjust get up one day and say,"I wanna walk on land"and now here we are.Like, it just miraculouslyturns its gills to lungsand can walk."Even though we can't sayprecisely what things were likeat that critical moment,that there are creaturesin the world that still displaysome of those characteristics.There are creatures called lungfish,which can crawl shortdistances through the mudto get from one pool to another.We are all familiar with thatcartoon image of evolutionwith the creature emerging from the water,and then progressingthrough a series of formsuntil there's a human being at the end.It's the most destructive cartoonin the history of science,because it gives us this false ideathat evolution is a linearprogression of one formreplacing the other alongthe path when in fact,it's much messier, more complex,and more wonderful than that.So yes, there was some creaturethat first began to emergefrom those watery depthsonto land, but that ledto a great diversity of different pathwaysonce that transition took place .@StartSOLE asks, "How willthe human species evolve?"The future of ourspecies is a big questionand open to question, but we know a lotabout human evolutionfrom looking at the past,and the story of human evolutionis really, in many ways,the story of brain sizeand each time we've seensome increase in thecapacity of our brains,biologists and anthropologistshave associated thatwith some change in humanbehavior that allowed usto gain more calories because brain tissueis what physiologists callmetabolically expensive.It takes a lot of fuel to run a brain.As many as 20% of our dailycalories go to fuel somethingthat's only 2% of our body weight.So if you want a bigger brain,you're going to have to havemore calories to run it, andwe've seen that through timeas our species has adopted newcharacteristics, new traits,new habits that have given us more to eat.Those things include tooluse and social behaviorsand cooking the food, so now,we are at a period of timewhere food, for many people, is plentiful,calories are plentiful.One question for futurebiologists then will behow did that change the human brain?@FlyBehaviour asks,"Mutant corn for dinner!Anyone know what mutationwould likely causethe double sized kernels?"Well, we don't know ifit's a mutation at allbecause sometimes corn or other plantsrespond in strange wayslike that to diseaseor bacteria or fungi, so we can't saywhat's making those colonelslarge in that situation,but whoever gets that ear for dinner,will have a bonus.@CherylRofer asks, "CanCRISPR save bananasfrom the fungal threat?Serious question for biology tweeps."It's a serious question foranyone who loves bananas.The common banana that webuy in the grocery storeis called the Cavendish banana,and unlike many other fruits in the store,the Cavendish bananas arenot produced from seedsand traditional crop breeding.A banana plant produces offshootsthat are easy to separatefrom that plant that are clonesof the banana plant itself,so if you find a bananathat has the characteristicsthat will be successful, commercially,it lasts a long time, it has good flavor,you can ship it around theworld to grocery stores,that is a truly valuablefruit, and that's whythe Cavendish banana is sopopular and why it's producedvia cloning so, when there is a threat,like this fungus that lives in the soiland it destroys theCavendish banana plant,they're all susceptible tothat fungus in the same way.CRISPR is a tool in molecular biologythat's used for turning on orturning off particular geneswithin the genome of aspecies, so if there is a genecurrently turned offin the Cavendish bananathat could be turned onagain to provide resistance,that is a possiblesolution to this problem.@A_C_Ella asks, "Fridaydebate in the office.Do plants grow fromthe bottom or the top?"Well, typically plants grow from the top,but there are situationsthat we're very familiar withwhere that growing part ofthe plant is lowered down,and we see that in our own lawns.Grasses have evolvedto grow from the bottomin response to grazing byanimals and more recentlyby the cutting of lawnmowersso that that leaf that you seewhen we cut it off willbe replaced from below.But most plants, like afir tree or an apple tree,are growing from the tips of their shoots.@Kbaumlier asks,"How does climate change affect wildlife?"We often summarize theimpacts of climate changeon plants and animalswith the acronym, MAD,short for "move, adapt ordie", and we see examplesof all three of thoseplaying out in nature,all around us.Between 25 and 85% ofspecies on this planetare now moving, shifting their rangesin response to climate change,looking for the temperaturesand conditions that they're used to.Many other species areadapting by changing dietsor behaviors to try tocope with this crisis.And yes, some species aredying and going extinct.And we also see speciesstruggling to adaptand adjust theirrelationships to one another.A fascinating example recentlyout of Gabon in Africa,where, for the first time,scientists observed chimpanzeesattacking a group ofgorillas, and in fact,even killing one of the gorillas.One of the reasons this may be happening,one of the theories, isthat there is now a shortageof fruit and other foodsfor those creaturesin that forest because of climate changecreating a new hypercompetitive environmentfor those two species thatused to coexist peacefully.@NekoMiller asks, "Blue eyes are weird."What is AF?I'm sorry.How do I?- [Production Crew Member] Uh...[Production Crew Member Laughs][beep]- Oh, as [beep].Can I say that?Or what do I say?@NekoMiller asks, "Blue eyes are weird AF.Like honestly, how does amutation like that even happen?"Mutations in biology occur in the DNAwhen it's being copied.It's not a perfect process.Mistakes are made.Oftentimes, those mistakeslead to new featuresin the organism.Usually, they're not very usefuland they disappear over time,but sometimes they can imparta benefit and they persist.This is one of the fundamentalways that new traitsare introduced into theevolutionary process.Blue eyes were introducedin that way fairly recentlyin human evolution.They have persisted, butno one's quite sure yetwhat the advantage of blue eyes may be.@TarrahLuzuriaga asks,"How do extinct speciescome back to the world?"Short answer, they don't.They're extinct, but thereare efforts underway nowto try to recreate or bringback some extinct specieslike the wooly mammoth from ancient DNA.It's still a work inprogress, a long way off,but some experts are workingon that very question.@LaurenRPeters asks, "If wehave evolved from monkeys,why are they not extinct?"Mm.When new species evolve,it's not necessaryfor them to replace thespecies they evolved from.In fact, it's more commonfor new species to existside-by-side with manyclosely-related species.@karu1402 asks, "Is the numberof genetically differenthuman beings that can be formed finite?"People are often curious ifthere might be a doppelganger,someone almost exactly like them out therein the world today, orat some point in history,and the fact is we can bepretty close, genetically,but every individual is indeed unique.When you consider the numberof genes in the human genome,20,000, 30,000, but also consideringthe number of base pairsin those DNA molecules,you're talking about billionsof different combinations.On top of that, it's notjust the genes themselvesthat are crucial, but howthose genes are expressed.All of those things can bedifferent among individuals.We're not going to runout of unique individualsanytime soon.@IBIS_journal asks,"What makes #penguin feathers ice-proof?"They're not just ice-proof.They are waterproof,structurally waterproof,and biologists still aren'tsure exactly how that works,but if you lookmicroscopically at the veinsof those feathers, you seethat they trap all sortsof small air pocketsand it may be that airpreventing water movingthrough the feather.That intricate feather veinhas thousands and thousandsof individual placeswhere the feather surfaceis pushing against the naturalsurface tension of the water.Either way, you don't have to worryabout penguins getting wet on their skin.@r_heisman asks, "Whatare some of your favoriteunsolved mysteries in biology?Interpret however you like."One of the great mysteries thatwe've really only discoveredsomewhat recently is just howmysterious our own genome is.When the human genomeproject sequenced our DNA,I think many people thought we would havethe recipe book for howto make a human being,but it turned out tobe far more complicatedthan anyone thought, becauseit's not just the sequenceof the genome, but it'sthe shape of the molecule.It's the genes.It's the patches of DNA aroundthe genes that control them.It's all sorts of thingsthat combine to seehow those genes are expressedand what makes us human.But you don't even have togo into molecular geneticsto find mysteries.They're all around us.A constant reminder that there's so muchto learn about ourselves and about nature,consider something as familiarto all of us as yawning.We still don't understand why people yawn.@michaelmccollor asks,"How did Darwin knowall that evolution stuff?"He didn't know.He learned it as he traveledand explored his worldbecause, in the 19th century,it was still widely assumedthat everything was createdvery recently, if you will,by the hand of God, andso Darwin was fascinatedby geology and how therewere species in the rocksin fossils that were no longerpresent in the modern world.He came up with the idea ofevolution by natural selection,would help explain howthings changed through time,and how you had this greatdiversity of life on the planet,and it was a radical idea at the time.He sat on it for years and yearsbefore finally publishinghis theories because he knewthey would be controversial.@lonely_kino asks, "What is bioethics?The ethics of biology?"The answer is yes, and we need to thinkabout the ethics of biologyas our ability to domore and more develops over time.Technologically, we have theability now to change DNA.We have the ability tocombine species in new ways,so we must constantly ask ourselves,not only, "Can we do thesethings, but should we?"So those are all the questions for todayand we've covered a lot of ground.Thank you for watching Biology Support.[cymbal crashes]